[ISSUE FIXED, SEE EDIT 2]

Not running on Win11 but Win10 here.
It's been a year since GOG won't launch.
I didn't care much at first, but now with Phantom Liberty, I need it to run (cloud save, rewards, progression, success etc.)

Tried everything I could.
Deleted many times (%appdata% & registry)
Installed on different hard-drives (4)

Waiting for another answer from the support (14 days now, they answered first, but when I said that it wasn't working, no more sign of life. Coincidence or intentional ? I don't know, I'll wait).

I've lost hope, I'm so sad. I'm close to buy it again on Steam and leave GOG

EDIT :
They reached back to me, lovely dedication.
Still nothing to do (tried "clean boot mode" which I didn't before, still nothing happens)

EDIT2 :
I've had my issue fixed, just right now.
It looks like some programs can interfere with GOG GALAXY.
I unistalled them via the Windows' config panel (this simple)
Here are the list of deleted programs (i don't know which was interefering, but I believe 2 softwares were interefering with each others) :
- Advanced System Care
- Driver Booster (both are from the same company)
- Malware Bytes
And here I am again.
I tried every thing ; "clean boot mode", installed older version, installed on different harddrive, nothing worked.
So, try to unnistall every program that you can, that might interefere with your PC in anyway, and you should find it (antivirus, optimizer, whatever you can unistall, try it)

What worked for me was cleaning my registry. I used the free version of CCleaner and it found registry entries that had not been updated. After re-installing it then worked normally.

Considering CCleaner's history and the fact it's reported as malware several times, I'd not recommend it.